
From model to crop: functional characterization of SPL 8 in M. truncatula led to genetic improvement of biomass yield and abiotic stress tolerance in alfalfa
Author(s) -
Gou Jiqing,
Debnath Smriti,
Sun Liang,
Flanagan Amy,
Tang Yuhong,
Jiang Qingzhen,
Wen Jiangqi,
Wang ZengYu
Publication year - 2018
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12841
Subject(s) - medicago truncatula , biology , abiotic stress , mutant , shoot , botany , population , genetically modified crops , crop , agronomy , horticulture , transgene , gene , symbiosis , genetics , demography , sociology , bacteria
Summary Biomass yield, salt tolerance and drought tolerance are important targets for alfalfa ( Medicago sativa L.) improvement. Medicago truncatula has been developed into a model plant for alfalfa and other legumes. By screening a Tnt1 retrotransposon‐tagged M. truncatula mutant population, we identified three mutants with enhanced branching. Branch development determines shoot architecture which affects important plant functions such as light acquisition, resource use and ultimately impacts biomass production. Molecular analyses revealed that the mutations were caused by Tnt1 insertions in the SQUAMOSA PROMOTER BINDING PROTEIN ‐ LIKE 8 ( SPL 8 ) gene. The M . truncatula spl8 mutants had increased biomass yield, while overexpression of SPL 8 in M. truncatula suppressed branching and reduced biomass yield. Scanning electron microscopy ( SEM ) analysis showed that SPL 8 inhibited branching by directly suppressing axillary bud formation. Based on the M. truncatula SPL 8 sequence, alfalfa SPL 8 ( Ms SPL 8 ) was cloned and transgenic alfalfa plants were produced. Ms SPL 8 down‐regulated or up‐regulated alfalfa plants exhibited similar phenotypes to the M. truncatula mutants or overexpression lines, respectively. Specifically, the Ms SPL 8 down‐regulated alfalfa plants showed up to 43% increase in biomass yield in the first harvest. The impact was even more prominent in the second harvest, with up to 86% increase in biomass production compared to the control. Furthermore, down‐regulation of Ms SPL 8 led to enhanced salt and drought tolerance in transgenic alfalfa. Results from this research offer a valuable approach to simultaneously improve biomass production and abiotic stress tolerance in legumes.